The Boeing 737 MAX 8 model first flew on 29 January 2016 and entered service in 2017, making it one of the newest aircraft in Boeing's commercial airliner offerings, and the newest generation of Boeing 737.[4] As of February 2019, 376 aircraft of this model have been produced and one other had crashed, Lion Air Flight 610 in Indonesia in October 2018.[2][5][6][7] Following the accident, the 737 MAX series of aircraft was grounded worldwide by various airlines and government regulators around the world.

Accident[]

Flight 302 was a scheduled international passenger flight from Addis Ababa to Nairobi. The aircraft took off from Addis Ababa at 08:38 local time (05:38 UTC) with 149 passengers and 8 crew on board.[5] One minute into the flight, the first officer, acting on the instructions of the captain, reported a "flight control" problem to the control tower. Two minutes into the flight, the plane's MCAS system activated, pitching the plane into a dive toward the ground. The pilots struggled to control it and managed to prevent the nose from diving further, but the plane continued to lose altitude. The MCAS then activated again, dropping the nose even further down. The pilots then flipped a pair of switches to disable the electrical trim tab system, which also disabled the MCAS software. However, in shutting off the electrical trim system, they also shut off their ability to trim the stabilizer into a neutral position with the electrical switch located on their yokes. The only other possible way to move the stabilizer would be by cranking the wheel by hand, but because the stabilizer was located opposite to the elevator, strong aerodynamic forces were pushing on it. As the pilots had inadvertently left the engines on full takeoff power, which caused the plane to accelerate at high speed, there was further pressure on the stabilizer. The pilots' attempts to manually crank the stabilizer back into position failed. Three minutes into the flight, with the aircraft continuing to lose altitude and accelerating beyond its safety limits, the captain instructed the first officer to request permission from air traffic control to return to the airport. Permission was granted, and the air traffic controllers diverted other approaching flights. Following instructions from air traffic control, they turned the aircraft to the east, and it rolled to the right. The right wing came to point down as the turn steepened. At 8:43, having struggled to keep the plane's nose from diving further by manually pulling the yoke, the captain asked the first officer to help him, and turned the electrical trim tab system back on in the hope that it would allow him to put the stabilizer back into neutral trim. However, in turning the trim system back on, he also reactivated the MCAS system, which pushed the nose further down. The captain and first officer attempted to raise the nose by manually pulling their yokes, but the aircraft continued to plunge toward the ground.[8][9]

The aircraft disappeared from radar screens and crashed at almost 08:44, six minutes after takeoff.[10][2][11][12] Flight tracking data showed that the aircraft's altitude and rate of climb and descent were fluctuating.[13] Several witnesses stated the plane trailed "white smoke" and made strange noises before crashing.[14] The aircraft impacted the ground at nearly 700 mph.[8] There were no survivors.[5]

It crashed in the woreda (district) of Gimbichu, Oromia Region,[15] in a farm field near the town of Bishoftu, 62 kilometres (39 mi) southeast of Bole International Airport.[16] The impact created a crater about 90 feet (27 m) wide,120 feet (37 m) long, and wreckage was driven up to 30 feet (9.1 m) deep into the soil. Wreckage was strewn around the field along with personal effects and body parts.[8][17][18]

Emergency response[]

Shortly after the crash, police and a firefighting crew from a nearby Ethiopian Air Force base arrived and extinguished the fires caused by the crash.[19] Police cordoned off the site, and Ethiopian Red Cross personnel and air crash investigators moved in. Together with local villagers, they sifted through the wreckage, recovering pieces of the aircraft, personal effects, and human remains. Trucks and excavators were brought in to assist in clearing the crash site. Human remains found were bagged and taken to Bole International Airport for storage in refrigeration units typically used to store roses destined for export, before being taken to St. Paul's Hospital in Addis Ababa for storage pending identification.[17][20] Personnel from Interpol and Blake Emergency Services, a private British disaster response firm contracted by the Ethiopian government, arrived to gather human tissue for DNA testing, and an Israel Police forensics team also arrived to assist in identifying the remains of the two Israeli victims of the crash.[21][22] The Chinese railway construction firm CRSG, later joined by another construction firm, CCCC, brought in large scale equipment including excavators and trucks. They recovered both black boxes on the 11th of March, with the first being found at 9 am and the second flight recorder found at 1 pm respectively.[a][23][24] The black boxes were given to Ethiopian Airlines and were sent to Paris for inspection by the BEA, the French aviation accident investigation agency.[25]

The captain of the plane was Yared Getachew, 29, who had been flying with the airline for almost nine years[43] and had logged a total of 8,122 flight hours, including 1,417 hours on the Boeing 737.[c] He had been a Boeing 737-800 captain since November 2017, and Boeing 737 MAX since July 2018.[10] At the time of the accident, he was the youngest captain at the airline.[44] The first officer, Ahmed Nur Mohammod Nur, 25, was a recent graduate from the airline's academy with 361 flight hours logged, including 207 hours on the Boeing 737.[d][10][44]

Responses[]

Ethiopian Prime MinisterAbiy Ahmed offered his condolences to the families of the victims.[5] Ethiopian Airlines CEO Tewolde Gebremariam visited the accident site, confirmed that there were no survivors and expressed sympathy and condolences.[45] Boeing issued a statement of condolence.[46]

The Ethiopian parliament declared 11 March as a day of national mourning.[47] During the opening of the fourth United Nations Environment Assembly in Nairobi, a minute of silence was observed in sympathy for the victims.[48]PresidentMuhammadu Buhari of Nigeria, in his condolence message on behalf of the government and the people of Nigeria, extended his sincere condolences to Prime Minister Abiy Ahmed of Ethiopia, the people of Ethiopia, Kenya, Canada, China and all other nations who lost citizens in the crash.[49]

On 11 March, the FAA commented that the Boeing 737 Max 8 model was airworthy. However, due to concerns on the operation of the aircraft, the FAA ordered Boeing to implement design changes, effective by April.[50] It stated that Boeing "plans to update training requirements and flight crew manuals in response to the design change" to the aircraft's Maneuvering Characteristics Augmentation System (MCAS). The changes will also include enhancements to the activation of the MCAS and the angle of attack signal.[51] Boeing stated that the upgrade was developed in response to the Lion Air crash but did not link it to the Ethiopian Airlines crash.[52]

On 19 March, the U.S. Secretary of Transportation, Elaine L. Chao, sent a memo to the U.S. Inspector General asking him to "proceed with an audit to compile an objective and detailed factual history of the activities that resulted in the certification of the Boeing 737-MAX 8 aircraft."[53]

Flight International commented that the accident would likely increase unease about the Boeing 737 MAX felt in the aftermath of the Lion Air Flight 610 accident in October 2018, which similarly occurred shortly after take-off and killed everyone aboard.[54] Boeing shares dropped 11% over the weekend;[55] by 23 March, Boeing had lost more than $40 billion in market value, dropping some 14% since the crash.[56]

Groundings[]

After the Ethiopian Airlines crash, China and most other aviation authorities preceded the U.S. Federal Aviation Administration (FAA), the certifying agency for the MAX, in grounding the airliner over perceived safety risks. The FAA issued a Continued Airworthiness Notification to the International Community on March 11 and resisted pressure from U.S. lawmakers to ground the aircraft.[57][58] Boeing CEO Dennis Muilenburg called U.S. president Trump on March 12 to assure him the airplane was safe.[59]
On March 13, 2019, the FAA found similarities between the two accidents and grounded the plane.[60] About 30 MAX aircraft were flying in U.S. airspace at the time and were allowed to reach their destinations.[61] By March 18, regulators grounded all 387 MAX aircraft in service with 59 airlines worldwide and making 8,600 flights each week.[62] Several ferry flights were operated with flaps extended to circumvent MCAS activation.

The grounding subsequently became the longest ever of a U.S. airliner.[63] As of January 2020, another 400 newly-manufactured aircraft await delivery to airlines pending the aircraft's return to service.

Investigation[]

The MAX uses an adjustable stabilizer, moved by a jackscrew, to provide the required pitch trim forces. Generic stabilizer illustrated.

The Ethiopian Civil Aviation Authority (ECAA), the agency responsible for investigating civil aviation accidents in Ethiopia, has been investigating. The aircraft manufacturer, Boeing, stated that it is prepared to work with the United States National Transportation Safety Board and assist Ethiopian Airlines.[46] The United States Federal Aviation Administration will also assist in the investigation.[64]

Both the cockpit voice recorder and the flight data recorder were recovered from the crash site on 11 March.[65] The French aviation accident investigation agency BEA announced that it would analyze the flight recorders from the flight.[66] BEA received the flight recorders on 14 March.[67] On 17 March, the Ethiopia's transport minister Dagmawit Moges announced that "the black box has been found in a good condition that enabled us to extract almost all the data inside" and that the preliminary data retrieved from the flight data recorder show a clear similarity with those of Lion Air Flight 610 which crashed off Indonesia.[68]

On 13 March 2019, the FAA announced that new evidence found on the crash site and satellite data on Flight 302 suggested that the aircraft might have suffered from the same problem which the aircraft operating Lion Air Flight 610 had suffered from. Investigators discovered the jackscrew that controlled the pitch angle of the horizontal stabilizer of Flight 302, was in the full "nose down" position. The finding suggested that, at the time of the crash, Flight 302 was configured to dive, similar to Lion Air Flight 610.[69] Due to this finding, some experts in Indonesia suggested that the Indonesian National Transportation Safety Committee (NTSC) should cooperate with Flight 302's investigation team.[70] Later on the evening, the NTSC offered assistance to Flight 302's investigation team, stating that the committee and the Indonesian Transportation Ministry would send investigators and representatives from the government to assist with the investigation of the crash.[71]

Preliminary report[]

On 4 April 2019, the ECAA released the preliminary report on the crash.[10] The preliminary report does not specifically mention MCAS but rather states "approximately five seconds after the end of the ANU (aircraft nose up) stabilizer motion, a third instance of AND (aircraft nose down) automatic trim command occurred without any corresponding motion of the stabilizer, which is consistent with the stabilizer trim cutout switches being in the ‘’cutout’’ position".[10]

Approximately one minute into the flight, an airspeed of 238 knots (441 km/h; 274 mph) was selected. About 12 seconds later, the autopilot disengaged. The preliminary report asserts that the thrust remained at takeoff setting (94% N1) and the throttles did not move for the entire flight.[10][72] In the next 30 seconds the stabilizer trim moved 4.2 degrees nose down, from 4.6 to 0.4 units.[73] In the next 10 seconds the trim moved back up to 2.3 units as a result of pilot input and the pilots agreed on and executed the stabilizer trim cut-out procedure, cutting power to the trim motor operated by MCAS.[10]

Interim report[]

On 9 March 2020, the ECAA released an interim report on the crash.[74]

Reactions to the investigation[]

Statements from parties[]

Ethiopian Airlines said MCAS was "to the best of our knowledge" active when the aircraft crashed.[75][76] According to Ethiopian transport minister Dagmawit Moges, the crew "performed all the procedures repeatedly provided by the manufacturer but was not able to control the aircraft".[77][78][79] Bjorn Fehrm from Leeham News stated the preliminary report confirms "the Flight Crew followed the procedures prescribed by FAA and Boeing in Airworthiness Directive 2018-23-51",[73] released shortly after the Lion Air crash.

Boeing's CEO Dennis Muilenburg said on 29 April that if "you go through the checklist...it calls out actions that would be taken around power management and pitch management of the airplane. It also refers to the cutout switches, that after an activation that was not pilot-induced, that you would hit the cutout switches. And, in some cases, those procedures were not completely followed".[80][81][82]

A data spike in the flight data[10] led to speculations about a bird or other debris hitting the plane as it was taking off, shearing away the airflow sensor.[83] These speculations were dismissed by Ethiopian Airlines, and Chief investigator Amdye Ayalew Fanta stated there was no indication of such damage.[83][84][85][86]

On 25 April, The Aviation Herald submitted 25 questions that have arisen in the aftermath of the accident to the FAA's Flight Standardization Board (FSB) regarding their draft for certification of the Boeing 737 MAX aircraft.[1] Earlier, it stated that a copy of the version of section 2.6 of the Flight Operations Manual, "Operational Irregularities", in use by Ethiopian Airlines at the time of the crash was dated 1 November 2017 and did not include material from the Operator's Bulletin issued by Boeing on 6 November 2018.[1]

Expert analysis[]

Based on the preliminary report, The Aviation Herald comes to the conclusion: "Neither of the three crews" (JT-43, JT-610, ET-302) "would have been forced to react under time pressure in order to prevent a crash, [...] without the technical malfunctions [of the angle of attack sensors] and the nose down trim inputs."[1]

According to The Air Current aviation journal and The Seattle Times, the preliminary report shows the pilots initially followed the procedure to disable runaway trim, but the recovery effort did not succeed.[87][88] Pilots have demonstrated in simulator that the trim wheels cannot be moved in severe mis-trim conditions combined with a high airspeed.[89][90] As the pilots on Flight 302 pulled on the yoke to raise the nose, the aerodynamic forces on the tail's elevator would create an opposing force on the stabilizer trim jackscrew that would prevent the pilots from moving the trim wheel by hand.[83][88][91]

The resolution for this jammed trim issue is not part of Boeing's current 737 manual according to The Air Current.[87] The Seattle Times reports pilots on the 737-200 were trained for this failure, but later models became so reliable that this procedure was no longer necessary.[87][88]

Experts theorize that the difficulty to trim made it necessary for the flight crew to release the cutout, and try to use electronic trim in an effort to correct the out-of-trim configuration.[73][92] According to Bjorn Fehrm (Leeham News) and Peter Lemme at this time the airplane was flying "at 375kts and MCAS was never designed to trim at these Speed/Altitude combinations".[73][92]

Pilot analysis[]

John Cox, previously a 737 pilot and pilots' union safety representative, and Chesley Sullenberger, who successfully ditched US Airways Flight 1549 in the Hudson River, both did Flight Simulator replications of Flight 302. Cox described the rapid onset of unforeseen events as a "...breeding ground for confusion and task saturation." Sullenberger commented that "Even knowing what was going to happen, I could see how crews would have run out of time and altitude before they could have solved the problems."[93] While defending the pilots' actions, Sullenberger was also highly critical of allowing someone with only 200 hours of flight experience to be first officer.[94]

See also[]

Notes[]

^Yared had 1,417 hours on the Boeing 737 regardless of variant, however, he only had 103 hours on the Boeing 737 MAX.[10]Ethiopian names do not have family names, so Ethiopian people are addressed by their given names.

^Ahmed had 207 hours on the Boeing 737 regardless of variant, however, he only had 56 hours on the Boeing 737 MAX.[10]